%0 Generic
%A Cörlin, Philipp
%D 2015
%F heidok:19644
%R 10.11588/heidok.00019644
%T Tracing ultra-fast molecular dynamics in O_2^+ and N_2^+  with XUV–IR pump–probe experiments
%U https://archiv.ub.uni-heidelberg.de/volltextserver/19644/
%X Within this thesis, molecular dynamics of diatomic molecules is studied using the XUV–IR pump–probe technique. Here, a single extreme ultraviolet (XUV) photon created by high-harmonic generation ionizes the diatomic target molecule. The initiated dynamics is probed after a variable time delay by an ultrashort (12 fs) infrared (IR) laser pulse. The 3-dimensional momenta of all charged fragments are measured using a reaction microscope.  In an experiment on O_2, a nuclear wave-packet oscillation is observed on the binding potential-energy curve (PEC) of the O_2^+(a ^4Π_u) electronic state. By comparing  simulated results with experimental data, theoretically predicted PECs are tested. The experimental results are best reproduced if the wave packet is propagated on a  Morse potential adjusted to the experimental data. This demonstrates the sensitivity of our method and its ability to predict accurate PECs from the measured wave-packet  evolution.  In an N2 experiment, the pump–probe delay dependent yield of stable N_2^+ is observed. It is interpreted as a sequential double ionization via a highly excited antibonding cationic state. The dissociation of the intermediate state is temporally resolved and can be interrupted by multi-photon ionization with the IR pulse within ≈ 15 fs after XUV ionization.